I am starting this thread to try to compile info on performance mods for the GNG 450 watt brushless mid drive kite, I'd like to keep this uncluttered with only step by step instructions for mods, links to upgrade info for the GNG and part #s / sources of parts. Please no speculation of what might work as that is being discussed in the main GNG thread, just mods that are known to work well.
Thanks, D

This is a "do at your own risk" controller mod that has worked well for me although I am told that you may change or over ride the Low voltage cutoff ,since I am overvolting the controller at 14s lipo the LVC doesnt matter and I use a turnigy watt meter to monitor battery voltage.
I use a T-50 staple, sand the legs and pre tin with solder, pull the non wired end off the controller and you will see the shunt with an extra shunt slot outboard, its best to enlarge the holes to allow the staple legs to slightly pass through then solder the staple in place, I place shrink wrap over the staple for added protection. this increases the amps from 22 to about 27 and provides a noticable increase in torque, there are other methods of acomplishing this but this is what I have fisrt hand experience with.

This is how I did my primary chain conversion using these parts >>the parts are from TNCscooters.com , # spk-103240 for the 65 tooth , #spk-106012 for the drive sprocket , and 2 ft of # chn-105250 chain , you will have to find another supplier for a #25 halflink , I used the original large belt pulley and trimmed the outer edge off , I then made a bushing to help center the sprocket on the pulley and kept adjust it untill I had virtualy no runout,
once I was satisfied I hotmelt glued the sprocket to the pully to keep it in place and then drilled and bolted the sprocket on,
I remover the outer " washer" from the motor drive pulley simply by bending it off with pliers and used a new file with the motor turning at a relativly slow speed to turn down the pulley to 10mm, by going slow and checking my work often I ended up with a nice snug fit for the new sprocket and again zero runout, as the shaft gets smaller material is removed very fast so check often. this took less than two hours of careful work.
CLICK ON THE IMAGES FOR VIDEO
The drive sprocket had to be tapped for set screws and two flats were filed on the shaft for the setscrews to bite against once I had correct chain alignment. To have minimal slack in the chain I used a half link instead of a master link.
The result is a smooth running primary drive.

the tensioner was made from an old dirt bike chain roller cut down ,the spring from the original secondary drive tensioner which isnt needed there and scraps of aluminum.
So far under hard use this has held up perfectly and is almost as quiet as the belt with the added bonus of eliminating the huge power consumption of the belt system, with " Lighningrod's adjustable sheets I hoping to do away with the tensioner and save even more power from being wasted.

Wiring the magura 0-5k throttle for use with the GNG stock controller.
for my application I installed two 10k 15 turn cermets in the " In and " out wires to fine turn the throttle, Its been noted that Maguras can come with the gears incorrectly clocked, mine was and had to be dissasembled and the pot gear advance one tooth, this ended up having the motor just " crawling" with the throttle in the off position and both cermets at zero resistance, I increased resistance in the Red wires cermet to eliminate the crawling and then went back and forth between the two cermets to find the optimal settings, the result is no dead space at the bottom end of the twist and just a slight amount at the top end, the throttle response is very controllable and almost all of the twist action is now having an effect. Wire color code is Black to black, Red to Blue and Brown to Green with the cermets in the Red to blue and black to black wires.

teklektik wrote:What are the final resistances of the trimpots after adjustment and the resistance of the Magura itself between the wiper and 5v supply lead (ignore the Gnd connection)?

On the 20k setting on the multimeter the ground trimpot reads 1.29, the blue 1.19 and the throttle brown ( wiper) and blue is 2.96 when throttle is closed and zero when throttle is full open, I dont understand the relationship between these.

Denisesewa wrote:On the 20k setting on the multimeter the ground trimpot reads 1.29, the blue 1.19 and the throttle brown ( wiper) and blue is 2.96 when throttle is closed and zero when throttle is full open, I dont understand the relationship between these.

Thanks. I was looking to get a feel for the actual trimpot values and the effect of clocking the gears. Here's what we have:

So (just winging it and guessing at your Rb-t and Vcc) the average Magura has an Rb-t of about 5.2K so your Rb-c = 5.2 - 2.96 ~= 2.2K. This puts the total resistance from Gnd to C at about 3.5K - which is pretty large making the controller Vmin (wheel begins to creep) probably 2v or more. This value is normally around 1v (hall throttles typically have a 1-4v output range - more or less) and so explains the ZERO throttle dead zone issue you have been having. The GNG throttles may not be top of the line, but they don't appear entirely to blame - it looks like you probably have to twist through 1/3 of a hall throttle before the GNG controller gets enough voltage to notice...

Denisesewa wrote:On the 20k setting on the multimeter the ground trimpot reads 1.29, the blue 1.19 and the throttle brown ( wiper) and blue is 2.96 when throttle is closed and zero when throttle is full open, I dont understand the relationship between these.

Thanks. I was looking to get a feel for the actual trimpot values and the effect of clocking the gears. Here's what we have:

So (just winging it and guessing at your Rb-t and Vcc) the average Magura has an Rb-t of about 5.2K so your Rb-c = 5.2 - 2.96 ~= 2.2K. This puts the total resistance from Gnd to C at about 3.5K - which is pretty large making the controller Vmin (wheel begins to creep) probably 2v or more. This value is normally around 1v (hall throttles typically have a 1-4v output range - more or less) and so explains the ZERO throttle dead zone issue you have been having. The GNG throttles may not be top of the line, but they don't appear entirely to blame - it looks like you probably have to twist through 1/3 of a hall throttle before the GNG controller gets enough voltage to notice...

So I did some testing with the magura and have determined that the controller needs 1.25 volts to make the motor start turning and above 4 volts the controller must be going into an overvoltage safety mode which shuts things down, of course I can get reach these numbers using resistors BUT the controller also needs to see about 1 volt at closed throttle to activate, this leaves .20 to .25 volts of dead space inherent in the controller. I think I'll hook up the second stock controller which does not have a modified shunt and see if there is any differance although I cant see how the shunt would have anything to do with this, kinda hoping I just have a bad controller.

While I had the jackshaft disassembled to fit the new adjustable side sheets, I put 2 new good quality SS6201 2RS bearings on the jackshaft, and rebuilt the 12T freewheel with new (1/8” 3.17mm) ball bearings and grease. It’s only a 2-pawl freewheel but there didn’t seem to have excessive wear on the ratchet teeth/pawls. Despite the fact that there was very little lubrication in the freewheel. I have only used the GNG kit for a few hundred miles, but I did note that some of the ball bearings showed signs of wear, with a grey colour. I suspect they are not hardened chrome steel, like the ones I have replaced them with. It all seems to run quieter and smoother now

skyungjae has found a freewheel adapter for the GNG jackshaft (It has an 11mm diameter tip with a key). The stock jackshaft freewheel is weak and hard to find, and this $43 adapter allows the use of an off-the-shelf robust 30mm X 1.0 BMX freewheel. It changes the tooth-count from 12T to 13T, so thats slightly worse, but the BMX freewheels can take a pounding while also being easy and cheap to replace.

The 12T FW has shallow pawl engagement to allow the lowest possible tooth-count (an uses an odd thread for mounting), but a 12T is weak and sometimes hard to find when your 12T breaks. 13T FWs are common, robust and affordable. Here is a link showing the insides of a failed stock 12T, the quality of the base metal and also the welding to the shaft adapter appear to be made from metal taken from recycled Chinese beer cans: https://endless-sphere.com/forums/viewto ... 27#p786944

In the link below, full-throttle shows how to change the Low-Voltage-Cutoff (LVC) of the stock controller. The LVC is set to cut off power when the battery gets low. If you keep running after the battery gets low, you can permanently damage the battery, so this is important.

The stock LVC is set for a 48V battery, and the simple job of changing one or two inexpensive resistors will allow the stock controller to run at a higher voltage or a lower voltage. 36V and 52V systems are described, and the procedure to calculate other battery voltages is included. The controllers capacitors are for a max of 63V, so if you need more than 52V, you might consider the highly regarded XieChang controller from Lyen.

spinningmagnets wrote:skyungjae has found a freewheel adapter for the GNG jackshaft (It has an 11mm diameter tip with a key). The stock jackshaft freewheel is weak and hard to find, and this $43 adapter allows the use of an off-the-shelf robust 30mm X 1.0 BMX freewheel. It changes the tooth-count from 12T to 13T, so thats slightly worse, but the BMX freewheels can take a pounding while also being easy and cheap to replace.

the 12T FW has shallow pawl engagement to allow the lowest possible tooth-count (an uses an odd thread for mounting), but a 12T is weak and sometimes hard to find when your 12T breaks. 13T FWs are common, robust and affordable.

ES member LightningRods has designed (and begun having a professional shop make) a new mounting bracket set for the GNG kit. The two main benefits are that: the the belt and chain idlers are removed from the system. This streamlines the drive and also removes the significant 100W drag of the stock belt idler. The second benefit is that new mount is much stronger. The metal is only slightly thicker, but is also made from a higher quality of steel.

The upper set is a big improvement, and it allows the jackshaft to be moved for adjusting the belt tension, rather than use the stock idler wheel.

The lower set is also stronger than the stock mount, and allows the chain idler to be omitted. If you do not want both sets right away, the outer set is the most important to upgrade, whether you keep the belt or convert to a chain primary.

the stock 44T chainring allows the rider to pedal along with the bike if you are using 36V, but at 48V the motor is spinning too fast. This is not a problem, but at 48V and above, the E-bike becomes a "scooter-only" at full RPM's, and the pedals are like foot-rests.

The GNG freewheeling crank system does not use a conventional central spider, so changing the chainring to a larger tooth-count is complex. Several builders have glued a larger tooth-count chainring onto the stock chainring for proper alignment (they used a chainring with 5 arms, some chainrings have 4 arms), and the glue held the new chainring in place while the builder drilled new holes to make a solid connection with bolts.

I believe the stock 44T chainring was selected so the kit will fit many different frames (the stock smaller chainring is 38T). A larger chainring might hit the front of the chainstay when you try to install it. Use a sprocket diameter calculator to determine tha largest sprocket that can fit your frame before you commit to purchase it. This way, you can mock-up a cardboard proxy chainring to see if it will fit, before spending money.

Mod 2. Shorten cables where possible, add heavy gauge cable between battery and controller, and add deans plugs.
Nothing major there, just reducing the possibility of voltage losses, and having the ability to easily kill the power by pulling the deans plug.

Mod 3. Change to Cyclone Isis crank set and chain rings.
Much much better gear, stronger, smoother. I went through a couple of freewheels before changing to these. http://www.cyclone-tw.com/order-chainwheel.htm - 140mm ISIS B.B. 444432T3 pc chainwheel freewheel crank set
Straight swap gear, only need the lockring from the original GNG bb set.

Mod 5. Shunt mod. As per Denisesewa's first post, I opened up the front of the controller. With the bike lifted applied full throttle and applied the rear brake, watching the watt meter for maximum amp draw. Peaked around 22A as stock. I then added solder to the existing shunt (melted it on with a soldering iron) a little at a time until it would pull 32A with the same braked experiment.
Maximum output I'm seeing now is over 1500W. Hopefully the controller and battery BMS will cope or they'll be next on the upgrade path.

Hows this for a basic fairing mod, taken from the aircraft homebuilt industy for making an engine cowling. Create foam blocks around the unit mounted on the bike to make a rough square form, shape to the shape you want remember you need cooling, intake nearly the size of the motor, exit area should be slightly larger then the intake. Shape the left and right sides, remove form in two sections left and right. Use Sglass with build up strip method and a final sheet should smooth things out. S glass is the latest used in the aviation industry, not as good as carbon though cheaper, light weight and strong, plastic is cheap but sglass does not require tooling or expensive molds to make something.

http://www.sickbikeparts.com is a bolt on gas motor page, They have replacement crank parts and a heavy duty free wheel made in the usa, problem is it is bigger than the freewheel that comes with GNG kit. I saw a guy moded a crank with it but took some grinding work. Anyways we ban borrow from the bolt on gas market as it is already there. Nice part is local replacement parts. This is worth looking into. Might be able to find American side that will just fit together.

Check out these controllers

Infinion Controllers, this guy has the manufacturer custom order mod them for performance and durability.

Wide Voltage Range: As of July 2011, the regulator design on these controller circuits has been upgraded so that they will operate over full range of voltage with no need to open up and change onboard resistors. 19-60V with the 20A and 35A models, and 26-88V with the 25A and 40A models.
Better Mosfets: We supply the manufacturer with locally sourced mosfets that have significantly better characteristics than the stock models, which results in a controller that runs cooler and is more robust.
Reinforced Bus Bars: The power traces on the ciruitboard are reinforced with solid copper wire for better conductivity and less chance of burnt traces.

100V Capacitors: We have all of our controllers made with large 100V 105oC rated bus capacitors. These capacitors are better able to handle high ripple currents and don't need to be replaced if the controller is modified for 72V or higher operation.
Long Leads: The phase and battery cables are 120cm long, able to reach right to the motor and battery for easy disconnection of those items. They are also terminated with real (not knock off) Anderson Powerpoles.
Smaller Package: Because of the better mosfets, we can offer higher current capabilities in a smaller enclosure size.
On/Off Switch: These controllers have a rocker ON/OFF switch that shuts the controller off so that it draws no current. It eliminates the need for a high current switch inline with the battery pack, and it has much greater reliability than the latching 'push' style of button switch used by Crystalyte.
Full Speed Fwd/Rev Control: The direction of the hub motor can be reversed with a simple jumper on the 2 pin connector. This makes it compatible with all different styles of motors regardless of which way is their natural direction of rotation
Cycle Analyst Connector: Each controller has the 6-pin CA-DP connector for easy integration of the Cycle Analyst. We also include a printed label that has the measured RShunt value for that particular controller, so that calibration of the Cycle Analyst is a cinch.
Regenerative Braking: The controllers are configured for a maximum amount of regenerative braking when an ebrake lever is connected to the 4-pin connector, saving wear on brake pads and returning mechanical energy back to the battery pack

I am in the planning research stage of a build and think I am going to go with the 450 watt if I can get theses brackets and a custom crank. Heard of a lot of people breaking there cranks with the GNG kits.

Also if you are good with wire and solder over gaging wiring gives less resistance increasing efficiency and performance. Replacing small wiring or going extreem over gage wires will help.

Edit cooling mod taken from the racing industry, this requires you to take the motor apart. Its called roughing, unlike polishing you want to rough the internal surface. This increases the internal surface area. You could even grove parts like a heat sink. Thing is you do not want deep groves as this can cause air interference inside.

Denisesewa wrote:This is how I did my primary chain conversion using these parts >>the parts are from TNCscooters.com , # spk-103240 for the 65 tooth , #spk-106012 for the drive sprocket , and 2 ft of # chn-105250 chain , you will have to find another supplier for a #25 halflink , I used the original large belt pulley and trimmed the outer edge off , I then made a bushing to help center the sprocket on the pulley and kept adjust it untill I had virtualy no runout,
once I was satisfied I hotmelt glued the sprocket to the pully to keep it in place and then drilled and bolted the sprocket on,
I remover the outer " washer" from the motor drive pulley simply by bending it off with pliers and used a new file with the motor turning at a relativly slow speed to turn down the pulley to 10mm, by going slow and checking my work often I ended up with a nice snug fit for the new sprocket and again zero runout, as the shaft gets smaller material is removed very fast so check often. this took less than two hours of careful work.
CLICK ON THE IMAGES FOR VIDEO
The drive sprocket had to be tapped for set screws and two flats were filed on the shaft for the setscrews to bite against once I had correct chain alignment. To have minimal slack in the chain I used a half link instead of a master link.
The result is a smooth running primary drive.

the tensioner was made from an old dirt bike chain roller cut down ,the spring from the original secondary drive tensioner which isnt needed there and scraps of aluminum.
So far under hard use this has held up perfectly and is almost as quiet as the belt with the added bonus of eliminating the huge power consumption of the belt system, with " Lighningrod's adjustable sheets I hoping to do away with the tensioner and save even more power from being wasted.

How is the pedal cadence on this setup? Is the ratio close to stock?

Power is a fascinating thing, the more you have, the more you want, but the real power is having the restraint not to use it all at once...............Um...Yeah..

The harder you work.....The luckier you get!!

"People who say it can't be done are often interrupted by those that have already figured out how to do it!"

Its actually a bit lower than stock , my bikes are used almost exclusivly for off road with alot of slow speed technical climbing , the lower geared primary keeps the motor RPM in a happy place without going to extreme final drive gearing. I do peddle now and then but only when I need to help the motor from lugging to get over something ( lugging creates heat and is inefficient)
Anyway, it works for me, others have done this same mod , perhaps they will add their experiences.

Whiplash wrote:So you pedal slower? That seems perfect! Low speed climbing is what I'm after as well. Lots of goat trails and this is for my brothers to keep up with my mid drive MAC build. Thanks!

The primary side only changes motor rpm, to change cadence ratio you need to change the chainring ratio ( differance between the tooth count on inside and outside chainrings), there are several people who have done this although I dont know where those threads are discussed other than the main GNG topic.

Just ordered the TNCscooter parts to do the #25 conversion on my youngest brothers bike. He couldn't swingthe cost of LR'S new bbelt kit so I'm going to give this a shot since its only about $30 in parts!

Power is a fascinating thing, the more you have, the more you want, but the real power is having the restraint not to use it all at once...............Um...Yeah..

The harder you work.....The luckier you get!!

"People who say it can't be done are often interrupted by those that have already figured out how to do it!"